Prior radar indicators, such as the AN/SPA-25G available from, e.g. Cardion, Inc., Woodbury, N.Y. contain an integral scan converter which enables display of radar with graphic overlay on a high-resolution, high-contrast CRT. This type of radar indicator is designed to increase operator functional capability and yet decrease workload through efficient man-machine interface. The indictor solves all the range, bearing and plotting tasks associated with target tracking and navigation. Radar input, correlated with internally generated and operator selected graphic symbology, provides a tactical display for both CIC and bridge environments. Radar systems are also known which include digital scan converters, as well as external graphic image generation equipment. One such equipment is the ASDE-3 (Airport Surface Detection Equipment) available from the before noted Cardion, Inc., which is used for monitoring ground traffic at various domestic and foreign airports.
The current prior art solution for combining the radar images with the externally generated graphical images requires the use of a frame store which receives the output of the radar scan converter and a synchronization circuit having as an input the source of external graphic signal and then controls the readout of the image frame memory in a manner synchronized with the external graphic signal.
It is an object of the present invention to provide the functionality of the prior art system in a more simplified manner and making use, where possible, of generally available consumer-type equipment, thereby reducing cost without reducing reliability.